To disable mail message confirmation window(dialogue) you need to have cutmail.exe application in version 1.1. You need to edit Windows registry.
In 
HKEY_CURRENT_USER\Software\SIP\Cutter2000\Cutmail
create new value of type DWORD named PreviewMsg and set its value to 0.

After setting this all orders confirmation mails will be sent without any confirmation - in silent mode.